This invention relates to an iterative interpolation method for determining at least one interpolated image information value in an image that has a number of image regions arranged in a matrix-like fashion, comprising original image regions, to which one image information value has already been assigned, and comprising at least one image region to be interpolated.
In image processing, interpolation methods to determine an image information value for an image region are required for a variety of applications.
One application is the generation of frames from fields transmitted in the field of television engineering. Here, one interline with a number of pixels is interpolated between every two lines of a given field so as to obtain a frame. An interpolation method for generating such interlines is described, for example, in German patent applications DE 102 36 208 A1 (Hahn et al.) or DE 102 32 372 A1 (Hahn et al.).
Another application for an interpolation method is to increase image resolution. Here additional lines and columns are generated by interpolation between existing lines and columns of an image so as to increase image resolution. A method for this is described, for example, in U.S. Pat. No. 6,229,570 B1 (Bugwadia et al.).
Interpolation methods are also required for image transmission processes in which an image to be transmitted is divided into image blocks, then transmitted block by block. If a block is not transmitted due to a transmission error, its image content must be interpolated on the receiver side. One method for achieving this is described, for example, in Meisinger, Kaup: “Spatial Error Concealment of Corrupted Image Data Using Frequency Selective Extrapolation” [Örtliche Fehlerverschleierung von gestört empfangenen Bilddaten durch frequenzselektive Extrapolation], Electronic Media: 10th Dortmund Television Seminar, ITG-Fachbericht 179, pages 189-194, September 2003.
Another application for interpolation methods in image processing is increasing the resolution of a motion vector field. An approach is sufficiently known in image processing whereby an image that is part of an image sequence having multiple successive images is subdivided into individual image blocks and a motion estimation method is used to assign a motion vector to each of these image blocks. These vectors together form a motion vector field. This type of motion vector assigned to a block contains information indicating at which position the content of this block is located within the previous and/or following image of the image sequence. This information can be utilized for the motion-correct generation of intermediate images between two images of an image sequence. In motion estimation, it is desirable to obtain the smallest possible blocks to which each motion vector is assigned. This does, however, increase the computational cost of the motion estimation.
A known approach to limiting this computational cost is to increase the resolution of the vector field by dividing the initially present image blocks into smaller blocks to which motion vectors are assigned using an interpolation method that takes into account the motion vectors of the original larger blocks. One method for achieving this is described in U.S. Pat. No. 5,148,269 (de Haan et al.).
The goal of the invention is to provide an improved interpolation method for determining at least one interpolated image information value in an image that has a number of image regions arranged in a matrix-like fashion having original image regions to which an image information value has already been assigned, and having at least one image region to be interpolated.